Adhesive bonding sheet, semiconductor device using same, and method for manufacturing such semiconductor device

ABSTRACT

An adhesive bonding sheet having an optically transmitting supporting substrate and an adhesive bonding layer, and being used in both a dicing step and a semiconductor element adhesion step, wherein the adhesive bonding layer comprises:
         a polymer component (A) having a weight average molecular weight of 100,000 or more including functional groups;   an epoxy resin (B);   a phenolic epoxy resin curing agent (C);   a photoreactive monomer (D), wherein the Tg of the cured material obtained by ultraviolet light irradiation is 250° C. or more; and   a photoinitiator (E) which generates a base and a radical by irradiation with ultraviolet light of wavelength 200-450 nm.

This application is a Divisional application of prior application Ser.No. 11/596,923, filed Nov. 17, 2006, the contents of which areincorporated herein by reference in their entirety. No. 11/596,923 is aNational Stage Application, filed under 35 USC 371, of International(PCT) Application No. PCT/JP2005/008971, filed May 17, 2005.

TECHNICAL FIELD

This invention relates to an adhesive bonding sheet, the semiconductordevice using same, and method for manufacturing such semiconductordevice.

BACKGROUND ART

In the prior art, silver paste was mainly used at the junction of asemiconductor device and a supporting material for a semiconductordevice mounting. However, in recent years, due to the miniaturizationand improvement in performance of semiconductor devices, compactness andminuteness of a supporting material are getting required. Despite theserequirements, with silver paste, there were various problems, such asfaults in wire bonding due to protrusion or tilting of the semiconductordevice, the difficulty of controlling the thickness of an adhesivelayer, and formation of voids in the adhesive layer. In order to solvethese problems, filmy adhesives have come to be used in recent years.Filmy adhesive is used in the film piece sticking method or wafer backsurface sticking method.

In the film piece sticking method, a reel-like adhesive film is firstcut out to pieces by cutting or punching, and then stuck to a supportingmaterial. Subsequently, a semiconductor element which has been dicedinto pieces in a dicing step, is joined to the obtained supportingmaterial with the adhesive film to manufacture a supporting materialwith the semiconductor element attached, and a wire bonding step andsealing step are then performed to complete the semiconductor element.However, in the film piece sticking method, a dedicated assembly deviceis required to cut the adhesive film and stick it to the supportingmember, and assembly costs were higher than those of the method usingsilver paste.

On the other hand, in the wafer back surface sticking method, anadhesive film was stuck to a semiconductor wafer, and then stuck to adicing tape. This was cut into pieces in a dicing step to obtain asemiconductor element with adhesive attached. Next, the semiconductorelement with adhesive is joined to a supporting member, and heating,curing and wire bonding steps are performed to complete thesemiconductor device. In the wafer back surface sticking method, thesemiconductor element with adhesive attached, is joined to thesupporting member, so a device to cut the adhesive film into pieces isnot required, and moreover, the prior art assembly device for silverpaste may be used as it is, or by making a partial modification such asby adding a heating plate. Therefore, the wafer back surface stickingmethod is popular among assembly methods using filmy adhesive sinceassembly costs can be suppressed relatively low.

The semiconductor element is cut into pieces in this wafer back surfacesticking method by sticking it on a dicing tape on the filmy adhesiveside, and then performing a dicing step. The dicing tape used may bebroadly divided into a pressure-sensitive type and a UV type. Thepressure-sensitive tape normally has an adhesive coated on to apolyvinyl chloride or polyolefin base film. This dicing tape should havesufficient tackiness so that during cutting, the elements are notscattered by the rotation of the dicing saw. On the other hand, thisdicing tape should have a sufficiently low tackiness so that pickup canbe performed without adhesive sticking to the elements and withoutscratching the elements. After all this dicing tape should have contraryperformance depending on the steps. Therefore, when a pressure-sensitivedicing tape was used, various types of adhesive sheet having differenttackiness depending on the element size and processing conditions with asmall tolerance, had to be provided and these adhesive sheet are changedover for each step. Consequently, a large number of types had to be keptin stock, and inventory management was complicated. It was alsonecessary to change over the adhesive sheet for each step.

However, in recent years, semiconductor elements (in particular, CPU andmemory) have been progressing towards higher capacities, and thesemiconductor elements have been increasing in size. Moreover, inproducts such as IC cards or memory cards, memories are becomingincreasingly thinner. Due to the increasing size and thinness of thesesemiconductor elements, it is therefore no longer possible to have apressure-sensitive dicing tape which satisfies the contradictoryrequirements of fixing force (high tackiness) during dicing and peelingforce (low tackiness) during pickup.

Recently, a so-called UV type dicing tape is being widely used whichsatisfies these contradictory requirements, since it has a hightackiness during dicing, but when it is irradiated with ultravioletlight (UV) before pickup, it develops a low tackiness.

However, in the wafer back surface sticking method using a UV typedicing tape, two film sticking steps must be performed before the dicingstep which makes the operation complicated. In order to solve thisproblem, various wafer sticking adhesive sheets were proposed whichcombine a wafer fixing function with a semiconductor element stickingfunction (e.g., JP-B-1987034, JP-A-H08-239636, JP-A-H10-8001,JP-A-2002-212522 and JP-A-2004-43760). These sheets are adhesive bondingtapes having an adhesive bonding layer which satisfies the role of anadhesive film and the role of a dicing tape in one layer. These sheetspermits so-called direct die-bonding wherein, after the dicing step, thesemiconductor element is picked up with the adhesive layer remaining onthe back surface of the chip, and curing/sticking is performed byheating or the like. Hence, it is possible to omit the adhesive coatingstep.

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

However, the adhesion sheets which are described in for exampleJP-B-1987034 and JP-A-H08-239636 do not exhibit superior thermalresistance in the cured material, and there was room for betterreliability, e.g., thermal resistance, after assembly of thesemiconductor package.

An adhesive sheet which is described for example in JP-B-1987034,JP-A-H08-239636 and JP-A-H10-8001 includes a heat-activated latent epoxyresin curing agent in order to improve storage stability. However, asthe curing agent is hygroscopic, curing is accelerated by moisture whichreduces the usable time, so care was still required regarding storageconditions.

Further, in the adhesive sheets disclosed in for example JP-A-H10-8001,JP-A-2002-212522 and JP-A 2004-43760, various photoreactive monomers areused to cure the adhesive bonding layer by light irradiation and reducethe adhesive force with the semiconductor wafer. But since thephotoreactive monomers have only low thermal resistance afterultraviolet light irradiation, there was room for improving adhesiveforce (tackiness during heating) during heating and reflow resistance.

Thus, the traditional adhesive sheet contributes to simplification ofthe semiconductor device manufacturing process, however, it is stilllacking sufficient adhesive properties with good reflow resistance underthe stringent moisture and heating conditions (e.g., 85° C., 85% RH, 168hours) required in semiconductor packages.

It is therefore an object of the present invention, which was conceivedin view of the aforesaid problems, to provide an adhesive bonding sheetwhich sufficiently functions as a dicing tape in a dicing step, and hasan excellent join reliability in a step which joins a semiconductorelement to a supporting member. It is a further object of the presentinvention to provide an adhesive bonding sheet having the thermalresistance and moisture resistance required when mounting asemiconductor element having a large difference of thermal expansioncoefficient on a supporting member for semiconductor element mounting,and excellent operability. It is yet another object of the presentinvention to provide a manufacturing method which can simplify asemiconductor device manufacturing process.

Means for Solving the Problem

The present invention therefore relates to:

1. An adhesive bonding sheet having an optically transmitting supportingsubstrate and an adhesive bonding layer, and being used in both a dicingstep and a semiconductor element adhesion step, wherein the adhesivebonding layer comprises:

-   -   a polymer component (A) having a weight average molecular weight        of 100,000 or more including functional groups;    -   an epoxy resin (B);    -   a phenolic epoxy resin curing agent (C);    -   a photoreactive monomer (D), wherein the Tg of the cured        material obtained by ultraviolet light irradiation is 250° C. or        more; and    -   a photoinitiator (E) which generates a base and a radical by        irradiation with ultraviolet light of wavelength 200-450 nm.

2. The aforesaid adhesive bonding sheet wherein the polymer component(A) having a weight average molecular weight of 100,000 or moreincluding functional groups is a (meth)acrylic copolymer comprising0.5-6 weight % of epoxy group-containing repeating unit based on thetotal weight of the polymer component.

3. The aforesaid adhesive bonding sheet, comprising:

-   -   100 weight parts of the polymer component (A) having a weight        average molecular weight of 100,000 or more including functional        groups, 5-250 weight parts of the epoxy resin (B), the phenolic        epoxy resin curing agent (C), wherein the equivalence ratio of        phenolic hydroxyl groups in the phenolic epoxy resin curing        agent (C) per epoxy group in the epoxy resin (B) lies within the        range of 0.5-1.5, 5-100 weight parts of the photoreactive        monomer (D), wherein the Tg of the cured material obtained by        ultraviolet light irradiation is 250° C. or more, and 0.1-20        weight parts of the photoinitiator (E) which generates a base        and a radical by irradiation with ultraviolet light of        wavelength 200-450 nm.

4. The aforesaid adhesive bonding sheet wherein the surface free energyof the supporting substrate is 50 mN/m or less.

5. The aforesaid adhesive bonding sheet wherein the elastic modulus ofthe supporting substrate at 25° C. is 1000 MPa or less.

6. The aforesaid adhesive bonding sheet wherein the yield elongation ofthe supporting substrate at room temperature is 20% or more.

7. The aforesaid adhesive bonding sheet wherein the 90° peel adhesionstrength after ultraviolet irradiation of the adhesive bonding layerrelative to the supporting substrate is 10 N/m or less.

8. The aforesaid adhesive bonding sheet wherein the tack strength of theadhesive bonding layer at 25° C. is 15 gf or more.

9. The aforesaid adhesive bonding sheet wherein the supporting substratesatisfies the conditions expressed by the following equation (a):

T1×α1−T2×α2≦7000 ppm  (a)

where T1 is transfer temperature when manufacturing adhesive bondingsheet, α1 is linear expansion coefficient at the transfer temperature,T2 is room temperature and α2 is linear expansion coefficient at roomtemperature.

10. A semiconductor device wherein a semiconductor element and asupporting substrate for semiconductor mounting are adhered together byusing the aforesaid adhesive bonding sheet.

11. A method of manufacturing a semiconductor device, comprising stepsof:

(1) affixing the aforesaid adhesive bonding sheet having the supportingsubstrate and the adhesive bonding layer to a semiconductor wafer viaaforesaid adhesive bonding layer,(2) forming a chip with said adhesive bonding layer by dicing thesemiconductor wafer,(3) forming a semiconductor element with a curing adhesive bonding layerby irradiating said adhesive bonding layer of the chip with saidadhesive bonding layer with ultraviolet light, and peeling saidsupporting substrate away from said semiconductor element with adhesivebonding layer; and(4) adhering said semiconductor element with adhesive bonding layerafter peeling said supporting substrate to the supporting member formounting the semiconductor element via said adhesive bonding layer.

EFFECTS OF THE INVENTION

Since the photo-curing adhesive bonding sheet of the present inventionhas the aforesaid structure, it has superior room temperature stickingproperties, dicing properties and reflow cracking resistance, so it issuitable for use as an adhesive resin for fixing electronic materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view showing an adhesive bondingsheet according to the present invention.

FIG. 2 is an upper surface view showing one example of the adhesivebonding sheet according to the present invention.

FIG. 3 is a cross-sectional view through a line X-X in (b) of FIG. 2.

FIG. 4 is a schematic cross-sectional view showing one example of thelayer structure of the adhesive bonding sheet of the present invention.

FIG. 5 is a schematic cross-sectional view showing a method of measuringa contact angle.

FIG. 6 is a schematic view showing a method of measuring an elasticmodulus, and a graph showing a method of defining a yield elongation.

FIG. 7 is a schematic cross-sectional view showing how the adhesivebonding sheet of the present invention is laminated onto a wafer.

FIG. 8 is a view showing a method of measuring 90° peel strength.

FIG. 9 is a schematic cross-sectional view showing a method of measuringtack load.

FIG. 10 is a schematic cross-sectional view showing a typical use of theadhesive bonding sheet of the present invention.

EXPLANATION OF REFERENCE NUMERALS

1: adhesive bonding sheet; 2: supporting substrate; 3: adhesive bondinglayer; 4: protective film; 5: edge part; 6: liquid sample (water andmethylene iodide); 7: measuring sample; 8: ring; 9: semiconductor wafer;10: dicing saw; 11: suction collet; 12: semiconductor element mountingsupporting substrate; 13: seal material; 14: solder ball; 15: wire bond;16: semiconductor device; 17: probe; 91, 92, 93: semiconductor element;A: semiconductor wafer; θ: contact angle.

BEST MODES FOR CARRYING OUT THE INVENTION

An adhesive bonding sheet 1 according to the present invention has astructure wherein an adhesive bonding layer 3 is provided on anoptically transparent supporting substrate 2 as shown in FIG. 1, and theadhesive bonding layer being further laminated with a protective film 4if required. FIG. 2 is an upper surface view showing one example of theadhesive bonding sheet of the present invention. The adhesive bondinglayer may be provided on the whole of the supporting substrate as shownin (a) of FIG. 2, or the adhesive bonding layer may first be cut to theshape of a semiconductor wafer to which it is to be stuck as shown in(b) of FIG. 2 (in FIG. 2, the protective film is not shown).

FIG. 3 is a cross-sectional view through a line X-X in (b) of FIG. 2. Inthese figures, plural adhesive bonding layers 3 are precut to a sizeslightly larger than the semiconductor wafer before lamination on therectangular supporting substrate 2. An edge part 5 is a thicknessadjusting part which is provided so that, when such a rectangularadhesive bonding sheet is wound on a roller or the like, the center partof the sheet with the adhesive bonding layer is prevented from swellingup. The thickness adjusting part may comprise an identical material tothat of the adhesive bonding layer 3, may be laminated to form a verythin layer on the adhesive bonding layer 3, or may be formed of acompletely different material.

In the case of such a rectangular sheet, the width of the adhesivebonding sheet is not particularly limited provided that thesemiconductor wafer can be affixed to it. But it is preferably widerthan an 8 inch wafer or 12 inch wafer by 1-10 cm and more preferably 3-8cm from the viewpoint of operability and productivity. The length of theadhesive bonding sheet may be freely set depending on the dicing deviceand the like. But if it is too short, replacement becomes difficult,whereas if it is too long, the adhesive bonding sheet in the center partof the roller becomes squeezed which may give rise to thickness andshape deformations. Therefore, it is preferably normally of the order of10 m-200 m and more preferably 30-70 m.

In the adhesive bonding sheet of the present invention, the adhesivebonding layer comprises, for example, a polymer component (A) having aweight average molecular weight of 100,000 or more including functionalgroups, an epoxy resin (B), a phenolic epoxy resin curing agent (C), aphotoreactive monomer (D), wherein the Tg of the cured material obtainedby ultraviolet light irradiation is 250° C. or more, and aphotoinitiator (E) which generates a base and a radical by irradiationwith ultraviolet light of wavelength 200-450 nm. Hereafter, in thecontext of the present application, these components may be abbreviatedas polymer component (A), epoxy resin (B), epoxy resin curing agent (C),photoreactive monomer (D) and photoinitiator (E), or simply as component(A), component (B), component (C), component (D) and component (E).

It is suggested that the reasons why the aforesaid adhesive bondingsheet can resolve the above problems are as follows.

(1) Because the polymer component (A) having a weight average molecularweight of 100,000 or more including functional groups and the epoxyresin (B) are not miscible with each other, and tend to form a so-calledsea-island structure, thus, low elasticity, adhesive properties,operability and high temperature reliability can be obtained.(2) Because by using both of the phenolic epoxy resin curing agent (C)and the photoreactive monomer (D), wherein the Tg of the cured materialobtained by ultraviolet light irradiation is 250° C. or more, superiorthermal resistance and reflow resistance can be obtained.(3) Because the film which have both reactivity and superior storagestability can be obtained. In other words, due to the use of thephotoinitiator (E) which generates a base and a radical by irradiationwith ultraviolet light of wavelength 200-450 nm in the presence of thephenolic epoxy resin curing agent (C) and the photoreactive monomer (D),wherein the Tg of the cured material obtained by ultraviolet lightirradiation is 250° C. or more, when light is not irradiated, the epoxyresin and photoreactive monomer hardly react together and superiorstorage stability can be obtained. On the other hand, if light isirradiated, a photoreaction of the photoreactive monomer (D) isaccelerated, and an epoxy resin curing accelerator generates, thus,curing reaction of the epoxy resin proceeds smoothly when heated in thiscondition.

Hereafter, the components will be described in more detail.

From the viewpoint of adhesion improvement, the polymer component (A)having a weight average molecular weight of 100,000 or more includingfunctional groups preferably contains a functional group such as epoxy(for example, glycidyl), acryloyl, methacryloyl, carboxyl, hydroxyl orepisulfide, and among these, from the viewpoint of cross-linkingproperties, glycidyl is preferred. Specifically, the component (A) maybe a (meth)acrylic copolymer containing glycidyl group having a weightaverage molecular weight of 100,000 or more, which is copolymerizedusing glycidyl acrylate or glycidyl methacrylate as a starting materialmonomer. From the viewpoint of reflow resistance, the component (A) ispreferably immiscible with the epoxy resin. However, miscibility isdetermined not only by the properties of the polymer component (A), so acombination is selected wherein the two moieties are immiscible. In thepresent invention, the aforesaid glycidyl group-containing (meth)acryliccopolymer denotes both a glycidyl group-containing acrylic copolymer anda glycidyl group-containing methacrylic copolymer.

Such a copolymer may be, for example, a (meth)acrylic ester copolymer oran acrylic rubber, and an acrylic rubber is more preferred. Acrylicrubber has an acrylic acid ester as its main component, and it is arubber mainly comprising a copolymer of butyl acrylate andacrylonitrile, or a copolymer of ethyl acrylate and acrylonitrile. Thecopolymer monomer may, for example, be butyl acrylate, methyl acrylate,ethyl acrylate, methyl methacrylate, ethyl methacrylate oracrylonitrile.

If a glycidyl group is selected as a functional group, glycidyl acrylateor glycidyl methacrylate is preferably used as the copolymer monomercomponent. Such a glycidyl group-containing (meth)acrylic copolymerhaving a weight average molecular weight of 100,000 or more can bemanufactured by selecting a suitable monomer from the aforesaidmonomers, or a commercial product (e.g., Nagase ChemteX HTR-860P-3,HTR-860P-5) can also be used.

In the polymer component (A) having a weight average molecular weight of100,000 or more including functional groups, the number of functionalgroups are important, because it affects the cross-linking degree, anddiffers depending on the resin used. For example, if the polymercomponent is obtained as a copolymer of plural monomers, the amount offunctional group-containing monomers used as starting materials ispreferably of the order of 0.5-6.0 weight %, based on the total amountof the copolymer.

If a glycidyl group-containing acrylic copolymer is used as component(A), the amount of glycidyl group-containing monomer (in the context ofthe present application, it is synonymous with the amount of glycidylgroup-containing repeating unit and the amount of epoxy group-containingrepeating unit) such as glycidyl acrylate or glycidyl methacrylate usedas starting materials is preferably 0.5-6.0 weight %, more preferably0.5-5.0 weight % and still more preferably 0.8-5.0 weight % of thecopolymer, based on the total amount of the copolymer. If the amount ofglycidyl group-containing monomer is within this range, smoothcross-linking of the glycidyl groups take place, thus tackiness can bemaintained while gelling can be prevented. Also, since it is immisciblewith the epoxy resin (B), it has excellent stress mitigation properties.

If a glycidyl group-containing acrylic copolymer is synthesized, otherfunctional groups may be introduced into the glycidyl acrylate orglycidyl methyl acrylate to be used as the monomer. The mixing ratio inthis case is determined by taking account of the glass transitiontemperature (hereafter, “Tg”) of the glycidyl group-containing(meth)acrylic copolymer, Tg preferably being −10° C. or more. If Tg is−10° C. or more, the tackiness of the adhesive bonding layer in B-stageis satisfactory and there are no problems regarding handling.

When the polymer component (A) having a weight average molecular weightof 100,000 or more including functional groups is a glycidylgroup-containing acrylic copolymer obtained by polymerizing theaforesaid monomers, the polymerization method is not particularlylimited, and may be for example a method such as pearl polymerization orsolution polymerization.

In the present invention, the weight average molecular weight of thepolymer component (A) is 100,000 or more, but preferably300,000-3,000,000, more preferably 400,000-2,500,000 and still morepreferably 500,000-2,000,000. If the weight average molecular weight iswithin this range, suitable strength, flexibility and tackiness areobtained when the material is fashioned into a sheet or film, and sinceflow properties are satisfactory, circuit filling properties of thewiring can be maintained. In the present invention, the weight averagemolecular weight is measured by gel permeation chromatography and is avalue obtained by conversion using a standard polystyrene calibrationcurve.

The epoxy resin (B) used in the present invention is not particularlylimited provided that it cures and sticks, and for example any of theepoxy resins listed in the Epoxy Resin Handbook (Masaki Shinpo, NikkanKogyo Shimbun) may be used. Specific examples are bifunctional epoxyresins such as bisphenol A epoxy, and novolak epoxy resins such asphenol novolak epoxy resin and cresol novolak epoxy resin. Other resinsknown in the art such as polyfunctional epoxy resins, glycidyl amineepoxy resins, heterocyclic ring-containing epoxy resins and aliphaticepoxy resins may also be used.

Examples of bisphenol A type epoxy resins are Japan Epoxy Resins Co.,Ltd. Epicoat 807, 815, 825, 827, 828, 834, 1001, 1004, 1007, 1009, DowChemicals DER-330, 301, 361 and Toto Kasei Co., Ltd. YD8125, YDF8170.Examples of phenol novolak type epoxy resins are Japan Epoxy Resins Co.,Ltd., Epicoat 152, 154, Nippon Kayaku Co., Ltd., EPPN-201 and DowChemical DEN-438. Examples of o-cresol novolak type epoxy resins areNippon Kayaku Co., Ltd. EOCN-102S, 103S, 104S, 1012, 1025, 1027 and TotoKasei Co., Ltd. YDCN701, 702, 703, 704. Examples of polyfunctional epoxyresins are Japan Epoxy Resins Co., Ltd. Epon1031S, Ciba SpecialtyChemicals Co., Ltd. Araldite 0163 and Nagase Chemical Co., Ltd. DenacolEX-611, 614, 614B, 622, 512, 521, 421, 411, 321. Examples of amine typeepoxy resins are Japan Epoxy Resins Co., Ltd. Epicoat 604, Toto KaseiCo., Ltd. YH-434, Mitsubishi Gas Chemicals Co., Ltd. TETRAD-X, TETRAD-Cand Sumitomo Chemicals, Ltd. ELM-120. Examples of heterocyclicring-containing epoxy resins are Ciba Specialty Chemicals Co., Ltd.Araldite PT810 and UCC ERL4234, 4299, 4221, 4206. These epoxy resins maybe used alone, or two or more may be used together.

In the context of the present invention, for the purpose of conferringhigh tackiness. Using bisphenol A type epoxy resin and phenol novolaktype epoxide resin as the epoxy resin (B) is preferred.

The usage amount of the epoxy resin (B) of the present invention ispreferably 5-250 weight parts relative to 100 weight parts of thepolymer component (A) having a weight average molecular weight of100,000 or more including functional groups. If the usage amount of theepoxy resin (B) is within this range, the elastic modulus andsuppression of flow properties during molding can be ensured, and hightemperature ease of handling is also sufficient. The usage amount of theepoxy resin (B) is more preferably 10-100 weight parts, and still morepreferably 20-50 weight parts.

As described above, the epoxy resin (B) is preferably immiscible withthe polymer component (A).

The phenolic epoxy resin curing agent (C) used in the present invention,when used for an adhesive bonding layer combined with an epoxy resin,has excellent impact resistance at high temperature and high pressure,and effectively maintains adhesion physical properties even under severeheat and moisture absorption conditions.

Examples of the component (C) are a phenolic resin such as phenolnovolak resin, bisphenol A novolak resin or cresol novolak resin. Morespecific examples are Dai Nippon Ink & Chemicals, Inc. Phenolite brandname: LF 2882, Phenolite LF 2822, Phenolite TD-2090, Phenolite TD-2149,Phenolite VH-4150 and Phenolite VH4170. These may be used alone, or twoor more may be used together.

In the present invention, to confer electrocorrosion resistance whenmoisture is absorbed, the usage amount of component (C) is preferablysuch that the equivalence ratio of phenolic hydroxyl groups in thephenolic epoxy resin curing agent (C) per epoxy groups in the epoxyresin (B) is within the range of 0.5-1.5, and more preferably such thatthis equivalence ratio is 0.8-1.2. If this equivalence ratio is toolarge, or even if it is too small, curing (crosslinking) of the resinbecomes insufficient, thus the glass transition temperature does notincrease. Consequently, moisture resistance and high temperatureelectrical properties tend to deteriorate.

In the adhesive bonding sheet of the present invention, if aphotoreactive monomer (D), wherein the Tg of the cured product obtainedby ultraviolet light irradiation is 250° C. or more is used, thermalresistance after ultraviolet light irradiation is high, thus tackinessand reflow resistance during heating becomes satisfactory. The Tg ofcomponent (D) is measured as follows. First, a photoinitiator is addedto component (D), and the cured product obtained by ultraviolet lightirradiation is molded into a rectangle having a size of about 5×5 mm tomanufacture a sample. The manufactured sample is measured by thecompression mode of a Seiko Instruments Ltd. (brand name: EXSTRA 6000)to determine Tg. If Tg is 250° C. or more, the thermal resistance of theadhesive bonding layer becomes excellent, and the sample can withstand atemperature of 250° C. or more in the reflow cracking resistance test.Therefore, reflow cracking resistance is satisfactory. From thisviewpoint of this, Tg of the cured product of the component (D) ispreferably 200° C. or more, and more preferably 250° C. or more. Stillmore preferably, the sample should be able to withstand lead-free solderof 260° C. or more. However, if Tg is too high, the sticking propertiesof the adhesive bonding sheet at room temperature after ultravioletlight irradiation tend to deteriorate, thus the upper limit ispreferably of the order of 350° C.

Specific examples of component (D) are polyfunctional acrylates such aspentaerythritol triacrylate, dipentaerythritol hexacrylate,dipentaerythritol pentacrylate, trimethylol propane triacrylate,isocyanic acid ethylene oxide-modified triacrylate, ditrimethylolpropane tetracrylate and pentaerythritol tetracrylate. Thesephotoreactive monomers may be used alone, or two or more may be usedtogether. From the viewpoint of residual monomer after ultraviolet lightirradiation, among polyfunctional moieties, dipentaerythritolhexacrylate or dipentaerythritol pentacrylate are preferred. Specificexamples are Shin-Nakamura Chemicals: A-DPH, A-9300.

If plural kind of components (D) are used, the Tg is the Tg of themixture which is measured by the aforesaid measurement method, and it isunnecessary that the Tg of the respective monomers is 250° C. or more.

The usage amount of the photoreactive monomer (D) of the presentinvention, wherein Tg of the cured product obtained by ultraviolet lightirradiation is 250° C. or more, is preferably 5-100 weight partsrelative to 100 weight parts of the polymer component (A) having aweight average molecular weight of 100,000 or more including functionalgroups. If the blending proportion is 5 weight parts or more, thepolymerization reaction of the photoreactive monomer due to ultravioletlight irradiation occurs easily, thus pickup properties tend to beenhanced. On the other hand, if it is larger than 100 weight parts, thelow elasticity of the polymer component no longer functions, the filmbecomes brittle, and moisture resistance and high temperature electricalproperties tend to deteriorate. From the same view point, the usageamount of component (D) is more preferably 10-70 weight parts, but stillmore preferably 20-50 weight parts relative to 100 weight parts of thecomponent (A).

The photoinitiator (E) which generates a base and a radical byirradiation with ultraviolet light of wavelength 200-450 nm of thepresent invention which generates a base and radicals due to irradiationby ultraviolet light of wavelength 200-450 nm is generally referred toas an α-aminoketone compound. This type of compound is disclosed forexample in J. Photopolym. Sci. Technol. Vol. 13, No. 12001, and itreacts as follows when irradiated with ultraviolet light:

Prior to ultraviolet light irradiation, there are no radicals presentfrom the α-aminoketone compound, thus a polymerization reaction of thephotoreactive monomer does not occur. Also, due to steric hindrance,curing of the thermosetting resin is not accelerated. However, whenultraviolet light irradiation is performed, the α-aminoketone compounddissociates, and due to the generation of radicals, a polymerizationreaction of the photoreactive monomer then occurs. Moreover, due todissociation of the α-aminoketone compound, steric hindrance decreasedand activated amine is produced. Therefore, it may be conjectured thatthis amine accelerates the curing of the thermosetting resin, and thatthis curing is accelerated by subsequent heating. Due to this effect,since radicals or active amines are hardly present prior to ultravioletlight irradiation, an adhesive bonding sheet having excellent storagestability at room temperature can be provided. The curing rate of thephotoreactive monomer or epoxy resin changes depending on the structureof the radicals and the amine produced by ultraviolet light irradiation,thus the photobase generating agent (E) can be determined according tothe species of component (B), component (C) and component (D).

The photo base-generating agent (E) may for example be2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one (CibaSpecialty Chemicals Co., Ltd., Irgacure 907),2-benzyl-dimethylamino-1-(4-morpholinophenyl)-butanone-1-one (CibaSpecialty Chemicals Co., Ltd., Irgacure 369), hexaryl-bisimidazolederivative (a substituent group such as halogen, alkoxy, nitro or cyanomay be substituted by phenyl group), or a benzoisoxazolone derivative.

In addition to the aforesaid base generating agent, a method may be usedwhich generates a base by photo-Fries rearrangement, photo-Claisenrearrangement or Curtius rearrangement, or Stevens rearrangement.

The aforesaid base generating agent may be used as a low molecularweight compound having a molecular weight of 500 or less, or a compoundintroduced into a polymer main chain and side chain. In this case, fromthe viewpoint of adhesive bonding property and fluidity of the adhesiveagent, the molecular weight is preferably a weight average molecularweight of 1000-100,000, but more preferably 5000-30,000.

In the adhesive bonding sheet of the present invention, the usage amountof the photobase generating agent (E) is preferably 0.1-20 weight partsrelative to 100 weight parts of the polymer component (A) having aweight average molecular weight of 100,000 or more including functionalgroups. If it is less than 0.1 weight parts, reactivity becomes poor andunreacted monomer may remain, whereas if it exceeds 20 weight parts,since the molecular weight increase due to the polymerization reactiondoes not function well, and a large amount of low molecular weightcomponents remain, reflow resistance may be affected. Therefore, theusage amount of component (E) is more preferably 0.5-15 weight parts,and still more preferably 1-5 weight parts.

Next, other components which may be contained in the adhesive bondinglayer in addition to the aforesaid component (A)-(E) will be described.To improve flexibility and reflow cracking resistance, a polymer resin(F) which is miscible with the epoxy resin may be added to the adhesivebonding layer which forms the adhesive bonding sheet of the presentinvention. From the viewpoint that substances which are not misciblewith the polymer component (A) improve reliability, such a polymer resinmay be for example a phenoxy resin, high molecular weight epoxy resin orsuper high molecular weight epoxy resin. These may be used alone, or twoor more may be used together. When a substance which is miscible withthe polymer component (A) is used as the epoxy resin (B), if a polymerresin which is miscible with the epoxy resin (F) is used, the epoxyresin (B) then becomes more miscible with component (F), so as a result,it may be possible to make the epoxy resin (B) and polymer component (A)immiscible.

The usage amount of polymer resin which is miscible with the epoxy resinis preferably 40 weight parts or less relative to a total of 100 weightparts of epoxy resin and phenolic epoxy resin curing agent. Within thisrange, Tg of the epoxy resin layer can be ensured.

To improve handling, enhance thermal conductivity, adjust melt viscosityand impart thixotropic properties, an inorganic filler may also be addedto the adhesive bonding layer forming the adhesive bonding sheet of thepresent invention. This inorganic filler is not particularly limited,but may be for example aluminum hydroxide, magnesium hydroxide, calciumcarbonate, magnesium carbonate, calcium silicate, magnesium silicate,calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride,aluminum borate whisker, boric nitride, crystalline silica ornon-crystalline silica. The shape of the filler is not particularlylimited. These fillers may be used alone, or two or more may be usedtogether.

Among these, to enhance thermal conductivity, inorganic fillers such asaluminum oxide, aluminum nitride, boric nitride, crystalline silica andnon-crystalline silica are preferred. From the viewpoint of adjustingmelt viscosity and imparting thixotropic properties, aluminum hydroxide,magnesium hydroxide, calcium carbonate, magnesium carbonate, calciumsilicate, magnesium silicate, calcium oxide, magnesium oxide, aluminumoxide, crystalline silica and non-crystalline silica are preferred. Toenhance fluidity when the film is heated, it is more preferable to use ananofiller.

The usage amount of inorganic filler is preferably 1-40 weight partsrelative to 100 weight parts of the adhesive bonding layer. If it isless than 1 weight part, the addition result may not be obtained, and ifit is more than 40 weight parts, the storage elastic modulus of theadhesive bonding layer may increase, its adhesive properties maydeteriorate, and electrical properties may deteriorate due to thepresence of voids.

To improve interface bonding between different materials, variouscoupling agents may also be added to the adhesive bonding layer formingthe adhesive bonding sheet of the present invention. Coupling agent maybe for example a silane coupling agent, titanium coupling agent oraluminum coupling agent.

The aforesaid silane coupling agent is not particularly limited, but maybe for example γ-methacryloxypropyltrimethoxysilane,γ-methacryloxypropylmethyldimethoxysilane,γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane,3-aminopropyl methyldiethoxysilane, 3-ureidopropyltriethoxysilane and3-ureidopropyltrimethoxysilane. These may be used alone, or two or moremay be used together. Specific examples are Nippon Unica A-189 andA-1160.

From the viewpoint of its effect, thermal resistance and cost, the usageamount of the aforesaid coupling agent is preferably 0.01-10 weightparts relative to 100 weight parts of the polymer component (A) having aweight average molecular weight of 100,000 or more including functionalgroups.

To improve insulation reliability when moisture is absorbed due toadsorption of ionic impurities, an ion capture agent may further beadded to the adhesive bonding layer forming the adhesive bonding sheetof the present invention. This ion capture agent is not particularlylimited, and may be for example a triazine thiol compound, a compoundknown as a copper poisoning prevention agent which prevents copper fromionizing and dissolving out, such as a bisphenol reducing agent, or aninorganic ion capture agent such as a zirconium type compound orantimony bismuth type magnesium aluminum compound.

From the viewpoint of its effect, thermal resistance and cost byaddition, the usage amount of the aforesaid ion capture agent ispreferably 0.1-10 weight parts relative to 100 weight parts of thepolymer component (A) having a weight average molecular weight of100,000 or more including functional groups.

(Method of Manufacturing Adhesive Bonding Sheet)

The adhesive bonding sheet of the present invention may be obtained bydissolving or dispersing the composition forming the adhesive bondingsheet in a solvent to produce a varnish, coating the varnish on asubstrate film, and then heating to remove the solvent.

As shown in FIG. 4, a varnish prepared by dissolving the adhesivebonding agent of starting material resin composition, comprising theaforesaid components in an organic solvent or the like, is coated by amethod known in the art such as knife coating, roller coating, spraycoating, gravure coating, bar coating or curtain coating on theprotective film 4 (referred to also as a release sheet), and drying toform the adhesive bonding layer 3. Subsequently, the opticallytransparent supporting substrate 2 is laminated to obtain the adhesivebonding sheet 1 comprising the release sheet (protective film), adhesivebonding layer and optically transparent supporting substrate.Alternatively, the adhesive bonding layer composition is coated directlyon the optically transparent supporting substrate by an identical methodand dried, and the protective film is then laminated to obtain theadhesive bonding sheet comprising the protective film, adhesive bondinglayer and optically transparent supporting substrate.

The optically transparent supporting substrate used in the adhesivebonding sheet of the present invention may be for example a plastic filmsuch as a polytetrafluoroethylene film, polyethylene film, polypropylenefilm or polymethylpentene film.

From the viewpoint of adhesive force between the supporting substrateand adhesive bonding layer, the optically transparent supportingsubstrate used in the adhesive bonding sheet of the present inventionpreferably has a surface free energy of 20-50 mN/m, and more preferably30-45 mN/m. If this surface free energy is less than 20 mN/m, theadhesive force at the interface between the optically transparentsupporting substrate and adhesive bonding layer goes down, and when theprotective film is removed, part of the adhesive bonding layer may bedetached from the supporting substrate. Alternatively, if it is morethan 50 mN/m, a peeling strength difference between supportingsubstrate/adhesive bonding layer and adhesive bonding layer/protectivefilm after exposure may not easily be manifested, the wafer fixingstrength may be too large and pickup properties may be impaired. In thepresent invention, the surface free energy is a value computed from thefollowing equations (1)-(3) from the measured value (refer to FIG. 5) ofthe contact angle θ relative to a liquid sample 6 (water and methyleneiodide) for a measurement sample 7 obtained by using Kyowa SurfaceChemicals Ltd. CA-Z.

72.8(1+cosθ1)=[(21.8)^(1/2)·(γ^(d))^(1/2)+(51.0)^(1/2)·(γ^(p))^(1/2)]  (1)

50.8(1+cosθ2)=[(48.5)^(1/2)·(γ^(d))^(1/2)+(2.3)^(1/2)·(γ^(p))^(1/2)]  (2)

γ=γ^(d)+γ^(p)  (3)

(in the equations, θ1 is a contact angle (deg) relative to water, θ2 isa contact angle relative to methylene iodide, γ is a surface freeenergy, γ^(d) is a dispersion component of the surface free energy, andγ^(p) is a polarity component of the surface free energy).

From the viewpoint of improving pickup properties, dicing properties andtransfer properties, the optically transparent supporting substrate usedin the adhesive bonding sheet of the present invention preferably has anelastic modulus at 25° C. of 10-2000 MPa. If it is less than 10 MPa, theperformance of the supporting substrate cannot be maintained, and if itis more than 2000 MPa, transfer tends to be poor, so subsequent pickupproperties may be affected. From the viewpoint of dicing properties,aforesaid elastic modulus is more preferably 50-1000 MPa, and still morepreferably 100-500 MPa. In the present invention, the elastic modulus ofthe optically transparent supporting substrate at 25° C. is determinedas follows. First, a rectangular film of sample size 1 cm×5 cm is fixedat intervals of 1 cm on both sides using an Orientech Co., Ltd.Tensilon, and a tensile strength measurement is performed at ameasurement speed of 100 mm/minute (see (a) of FIG. 6.). Using measuringresult of horizontal axis: elongation/%, vs. vertical axis: stress/MPa(see (b) of FIG. 6), the slope of the line joining the point where thesample begins to elongate and the stress (the point B) corresponding tothe point A of 1 mm elongation (3.3%) is taken as the elastic modulus ofthe supporting substrate.

The yield elongation of the optically transparent supporting substrateused for the adhesive bonding sheet of the present invention should beconsidered for smooth expansion. Yield elongation is a tensile propertywhich expresses the degree of elongation at the yield point as apercentage. The value of the yield elongation is preferably 5-100% ormore, and more preferably 20-80% or more. If the yield elongation isless than 5%, pickup tends to be hindered. In the present invention, thevalue of the elongation (point D) corresponding to the first peak value(point C) of stress in the aforesaid measurement results for the elasticmodulus ((b) of FIG. 6) is taken as the yield elongation of theoptically transparent support member.

Considering that the optically transparent supporting substrate used forthe adhesive bonding sheet of the present invention may be handled as asheet, due attention should be paid to its linear expansion coefficient.From the viewpoint of curvature, the linear expansion coefficient of thesupporting substrate preferably satisfies the condition expressed by thefollowing equation (a):

T1×α1−T2×α2<7000 (units:ppm)  (a)

where T1 is transfer temperature when manufacturing adhesive bondingsheet, α1 is linear expansion coefficient at the transfer temperature,T2 is room temperature and α2 is linear expansion coefficient at roomtemperature.

If the left-hand side of equation (a) exceeds 7000 ppm, curvatureincreases too much when the substrate is used as a sheet during handlingand handling properties deteriorate. From the same point of view, theleft-hand side of equation (a) is more preferably 5000 ppm or less, andstill more preferably 3000 ppm or less. In the present invention, thelinear expansion coefficients α1, α2 (units: ppm/° C.) are determined bya thermal analysis system of Seiko Instruments (brand name: EXSTRA 6000)using a film of sample size 4 mm×1 cm, in the tension mode, temperatureincrease rate: 10° C./min, measurement temperature: −20° C. to 180° C.In equation (a), “room temperature” means 25° C.

The solvent used to prepare the aforesaid varnish is not particularlylimited provided that it is an organic solvent, and is determined byconsidering the volatility during film manufacture from the boilingpoint. As specific examples, to prevent film curing from occurringduring film manufacture, relatively low boiling solvents such asmethanol, ethanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol,methyl ethyl ketone, acetone, methyl isobutyl ketone, toluene and xyleneare preferred. To improve coatability, relatively high boiling solventssuch as for example dimethyl acetamide, dimethylformamide,N-methylpyrrolidone and cyclohexanone are preferred. These solvents maybe used alone, or two or more may be used together.

To manufacture the varnish when an inorganic filler is added,considering the dispersibility of the inorganic filler, a stone mill,3-roller mill, ball mill and bead mill are preferably used, or acombination thereof can be used. The mixing time can also be shortenedby premixing the inorganic filler and low molecular weight startingmaterial, and then blending the high molecular weight starting material.Further, after the varnish has been prepared, air bubbles in the varnishcan be removed by vacuum degassing.

The thickness of the adhesive bonding layer is not particularly limited,but is preferably 3-200 μm. If it is thinner than 3 μm, stressmitigation becomes poor, and if it is thicker than 200 μm, it becomesuneconomical and the requirement to make the semiconductor device morecompact cannot be satisfied.

The thickness of the supporting substrate is not particularly limited,but is preferably 5-250 μm. If it is thinner than 5 μm, there is a riskof breaking the supporting substrate when a cut is made in thesupporting substrate during dicing, and if it is thicker than 250 μm, itbecomes uneconomical.

The total thickness of the adhesive bonding layer and supportingsubstrate is normally of the order of 10-250 μm. If the supportingsubstrate has the same or slightly greater thickness than that of theadhesive bonding layer, operability becomes better. Specificcombinations of adhesive bonding layer/supporting substrate (μm) are5/25, 10/30, 10/50, 25/50, 50/50, 50/75, and these may be suitablydetermined depending on the usage conditions and devices. To obtain thedesired thickness, the adhesive bonding sheet of the present inventionmay also comprise two or more adhesive bonding agent prepared separatelywhich are stuck together on the adhesive bonding layer side of theadhesive bonding sheet so as to improve fluidity during heating. In thiscase, the sticking conditions must be such that the adhesive bondinglayers do not peel away from each other.

When the adhesive bonding sheet having the aforesaid structure isirradiated with ultraviolet light, after ultraviolet light irradiation,the adhesive force between the supporting substrate and the adhesivebonding layer largely decreases, so the adhesive bonding sheet can beeasily picked up from the supporting substrate while the adhesivebonding layer is supported on a semiconductor element.

As a simple test for measuring pickup properties in the adhesive bondingsheet of the present invention, a 90° peel adhesion strength measurementcan be performed (at a measurement temperature of 25° C.). In thepresent invention, 90° peel adhesion strength measurement is performedas follows. First, as shown in (a) of FIG. 8, the adhesive bonding sheet1 is laminated on a wafer A, a cut is made to a width of 1 cm, thesubstrate 2 is cut and ultraviolet light irradiation is performed.Subsequently, as shown in (b) of FIG. 8, the 90° peel adhesion strengthis measured by performing a 90° peel of the adhesive bondinglayer/supporting substrate interface at a tension speed of 300 m/minute.From the viewpoint of pickup properties, the peel adhesion strength ispreferably 20 N/m or less, and more preferably 10 N/m or less.

As a simple test for measuring room temperature adhesion properties ofthe adhesive bonding sheet of the present invention, a tack loadmeasurement may be performed (FIG. 9). From the viewpoint of handlingand room temperature lamination properties, the tack load is preferably5-400 gf, and more preferably 10-200 gf. The tack load measurement ofthe present invention is performed using RHESCA tacking tester under themeasurement conditions of probe 17's diameter 5.1 mm, peeling rate 10mm/sec, contact load 100 gf/cm², contact time 1 s and at 25° C.according to JIS-Z-0237-1991.

After the adhesive bonding sheet of the present invention has beensubjected to a dicing step, the adhesive bonding sheet is irradiated byultraviolet light (UV) which polymerizes and cures the adhesive bondingsheet having ultraviolet light polymerizing properties, and reduces theadhesive force at the interface between the adhesive bonding sheet andsubstrate so that pickup of a semiconductor element can be performed. Anexample of using method for the adhesive bonding sheet according to thepresent invention will now be described referring to FIG. 10.

(a) of FIG. 10 shows the adhesive bonding sheet 1 comprising asupporting substrate 2, and an adhesive bonding layer 3 precut to thesame shape as a wafer and with a slightly larger surface area than thewafer on the supporting substrate 2.

Next, a semiconductor wafer 9 in preparation for dicing, is affixed atroom temperature or with heating to the adhesive bonding layer 3 of theadhesive bonding sheet 1 ((b) of FIG. 10), dicing is performed by adicing saw 10 ((c) of FIG. 10), and rinsing and drying steps are addedif required. At this time, the semiconductor element is kept well stuckto the adhesive bonding sheet, so the semiconductor element does notfall off between the aforesaid steps.

Next, the adhesive bonding sheet is irradiated by radiation so as tocause the adhesive bonding sheet, which has the property of polymerizingdue to radiation, to polymerize and cure ((d) of FIG. 10). The radiationmay be for example ultraviolet light, an electron beam or infraredlight. In (d) of FIG. 10, the case of ultraviolet light is shown. Theadhesive bonding sheet is irradiated with ultraviolet light from theadhesive bonding sheet surface having ultraviolet light polymerizingproperties. The irradiation intensity and irradiation amount increase ordecrease depending on the composition of the adhesive bonding sheet, butthe irradiation intensity is normally of the order of 3-100 mW/cm² andirradiation amount is normally of the order of 80-1000 mJ, which is anindication of the radiation amount required to effectively polymerizethe photoreactive monomer. At this time, the supporting substrate 2 ofthe adhesive bonding sheet should be transparent to ultraviolet light.In other words, in the context of the present invention, the term“optically transparent supporting substrate” means a supportingsubstrate which is transparent to the radiation used at this stage.

Subsequently, semiconductor elements 91, 92 and 93 obtained by dicingare picked up together with the adhesive bonding sheet after ultravioletlight curing by a suction collet 11 (FIG. 10( e)), pressed ontosemiconductor element mounting supporting substrate 12 at roomtemperature or while heating to 40-150° C. (FIG. 10( f)), and heated.Due to the heating, the adhesive bonding sheet develops a reliableadhesive force, which completes the adhesion of the semiconductorelement 91 and semiconductor element mounting supporting substrate 12.Also, as shown for example in FIG. 10( g), the semiconductor device isnormally subjected to a fixing step for making a wire bond 15, a stepfor sealing with a seal material 16 and a step for providing a solderball 14 and electrically connecting it to an external board(motherboard), and since it normally passes through one or more thermalhistory cycles, the aforesaid adhesive agent layer can also be heatedand cured using this thermal history.

EXAMPLES

Hereafter, the present invention will be described referring to specificexamples, but it should be understood that the invention is not to beconstrued as being limited in any way thereby.

Example 1

100 weight parts of HTR-860-P3 (Imperial Chemical Industries Ltd.,acrylic rubber containing glycidyl groups, molecular weight 1,000,000,Tg −7° C.), 5.4 weight parts of YDCN-703 (Toto Kasei Ltd., brand name,o-cresol novolak epoxy resin, epoxy equivalent 210), 16.2 weight partsof YDF-8170C (Toto Kasei Ltd., brand name, bisphenol F epoxy resin,epoxy equivalent 157), 15.3 weight parts of Plyophen LF2882 (DainipponInk Chemical Industries Ltd., brand name, bisphenol A novolak resin),0.1 weight parts of NUCA-189 (Nippon Unica Ltd., brand name,γ-mercaptopropyltrimethoxysilane), 0.3 weight parts of NUCA-1160 (NipponUnica Ltd., brand name, γ-ureidopropyltriethoxysilane), 30 weight partsof A-DPH (Shin-Nakamura Chemical Industries Ltd., brand name,dipentaerythritol hexacrylate), 1.5 weight parts of Irgacure 369 (CibaSpecialty Chemicals, brand name,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1-one: I-369)and cyclohexanone were mixed together with stirring, and vacuumdegassed. This adhesive varnish was coated on surface release-treatedpolyethylene terephthalate (Teijin Ltd., Teijin Tetron film: A-31) as aprotective film of thickness 75 μm, and heat-dried at 80° C. for 30minutes to obtain an adhesive bonding sheet. The adhesive bonding sheetwas laminated together with an optically transparent supportingsubstrate of thickness 100 μm (Ronseal, brand name, soft polyolefinfilm: POF-120A) to obtain an adhesive bonding sheet comprising aprotective film (surface release-treated polyethylene terephthalate),adhesive bonding layer and optically transmitting supporting substrate.

Example 2

An identical procedure to that of Example 1 was performed, except thatthe amount of photoreactive monomer (A-DPH) was changed to 50 parts inthe blending proportion of adhesive bonding components.

Example 3

An identical procedure to that of Example 1 was performed, except thatin the mixture of adhesive bonding components, the silane coupling agentwas not added.

Example 4

An identical procedure to that of Example 1 was performed, except thatthe supporting member was Gunze DDD (brand name) instead of POF-120A.

Example 5

An identical procedure to that of Example 1 was performed, except thatthe adhesive component HTR-860-P3 was replaced by HTR-860-P5 (NagaseChemteX Ltd., brand name, glycidyl group-containing acrylic rubber,molecular weight 800,000, Tg −10° C.).

Example 6

An identical procedure to that of Example 1 was performed, except thatin the blending proportion of the adhesive bonding components, YDF-8170was not added, and 5.5 weight parts of EXA-4850-150 (Dai Nippon InkChemicals Ltd., brand name, flexible and tough liquid epoxy resin, epoxyequivalent 450) was added.

Example 7

An identical procedure to that of Example 1 was performed, except thatthe photoreactive monomer in the adhesive bonding components, Irgacure369, was replaced by 1.5 weight parts of Irgacure 907 (Ciba SpecialtyChemicals, brand name,2-methyl-1(4-(methylthio)phenyl-2-morpholinopropane-1-one: I-907).

Example 8

An identical procedure to that of Example 1 was performed, except thatA-DPH in the adhesive bonding components was replaced by 30 weight partsof A-9300 (Shin Nakamura Chemical Industries Ltd., brand name,ethoxylated isocyanuric acid triacrylate).

Example 9

An identical procedure to that of Example 1 was performed, except thatthe supporting substrate was FHF-100 (Thermo Ltd., brand name, lowdensity polyethylene terephthalate/vinyl acetate/low densitypolyethylene terephthalate triple layer film) instead of POF-120A.

Comparative Example 1

An identical procedure to that of Example 1 was performed, except thatA-DPH, the photoreactive monomer in the adhesive bonding components, wasreplaced by BPE-200 (Shin Nakamura Chemical Industries Ltd., brand name,2.2-bis[4-(methacryloxy diethoxy)phenyl]propane).

Comparative Example 2

An identical procedure to that of Example 1 was performed, except thatA-DPH, the photoreactive monomer in the adhesive bonding components, wasreplaced by 30 weight parts of FA-321M (Hitachi Chemicals Ltd., brandname, ethylene oxide-modified bisphenol A dimethylacrylate).

Comparative Example 3

An identical procedure to that of Example 1 was performed, except thatthe photoreactive monomer in the adhesive bonding components was notadded.

Comparative Example 4

An identical procedure to that of Example 1 was performed, except thatthe photoinitiator in the mixture of adhesive bonding components was notadded. The compositions or the like of aforementioned Examples andComparative Examples are shown in Tables 1 and 2.

The examples and comparative examples were evaluated by the followingtest methods. The results are shown in Tables 3 and 4.

(1) Room Temperature Sticking Properties

An adhesive bonding sheet was stuck to a silicone wafer of thickness 280μm on a wafer mount, and the room temperature sticking properties wereevaluated. “A” shows that sticking property was satisfactory.

(2) Chip Scattering After Dicing

An adhesive bonding sheet was stuck to a silicone wafer of thickness 280μm, and the silicon wafer with adhesive bonding sheet was mounted on adicing device. Next, a semiconductor wafer was fixed on the dicingdevice, diced into rectangle of 3.2 mm×3.2 mm at a speed of 10 mm/sec,and the number of semiconductor chips which peeled away from theadhesive bonding sheet due to poor tackiness was measured.

(3) Pickup Properties

A semiconductor wafer was fixed on a dicing device, diced into rectangleof 3.2 mm×3.2 mm pieces at a speed of 10 mm/sec, the body to beirradiated was then disposed at a point with an irradiation of 50 mW/cm²using a Fusion exposure device (brand name: AEL-1B/M), the adhesivebonding sheet was irradiated from the substrate film side for 8 seconds,and it was examined whether or not the semiconductor chip with adhesivebonding layer could be picked up from the optically transparentsupporting substrate.

A: Almost all chips could be picked upB: 50-90% of diced chips could be picked upC: The number of diced chips which could be picked up was 50% or less.

(4) Initial Shearing Adhesion

A semiconductor wafer was fixed on a dicing device, diced intorectangles of 3.2 mm×3.2 mm at a speed of 10 mm/sec, irradiated byultraviolet light, and the semiconductor chip with adhesive bondinglayer was picked up from the optically transparent supporting substrate.It was then die-bonded to an organic substrate (PSR-4000, SR-AUS5,thickness of 0.2 mm) under the conditions of 180° C., 2 MPa, 30 sec, andpost-curing was performed at 175° C. for 5 hours to obtain a testsample. This test sample was held on a hot plate at 265° C. for 30seconds, and the shearing adhesive strength between the chip and organicsubstrate was measured.

(5) Reflow Cracking Resistance

The adhesive bonding sheet was die-bonded to a wiring board under theconditions of 100° C., 200 gf, 30 seconds, a semiconductor chip wasmolded to a predetermined shape using a sealing agent (HitachiChemicals: CEL-9700-HF10), and heat curing was performed at 175° C. and5 hours to obtain a package. The cured package was left under theconditions of 85° C./60% RH for 7 days, the package was passed throughan IR reflow furnace such that the maximum temperature of the packagesurface was 260° C. and this temperature was maintained for 20 seconds,and the cracks in the package were observed visually and by ultrasonicmicrograph. The number of cracks per 10 packages at this time wasrecorded.

A: packages with no cracksB: packages with cracks

TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Adhesive bonding (A)High molecular HTR-860-P3 100 100 100 100 — 100 100 layer weightcomponent HTR-860-P5 — — — — 100 — — (B) Epoxy resin YDCN-703 5.4 5.45.4 5.4 5.4 5.4 5.4 EXA-4850 — — — — — 5.5 — YDF-8170 16.2 16.2 16.216.2 16.2 — 16.2 (C) Curing agent LF2882 15.3 15.3 15.3 15.3 15.3 30.615.3 (D) Photoreactive A-DPH (250° C. or more) 30 50 30 30 30 30 30monomer A-9300 (250° C. or more) — — — — — — — (Brackets indicate Tg.)BPE-200 (75° C.) — — — — — — — FA-321M (150° C. or less) — — — — — — —(E) Photoinitiator I-369 1.5 1.5 1.5 1.5 1.5 1.5 — I-907 — — — — — — 1.5Silane coupling agent NUCA-189 0.1 0.1 — — 0.1 0.1 0.1 NUCA-1160 0.3 0.3— — 0.3 0.3 0.3 90° peel strength (N/m) after UV irradiation 2 1 2 6 3 75 Tack strength at 25° C. prior to UV irradiation 46 80 38 46 33 99 78Supporting Surface energy (mN/m) 33 33 33 36 33 33 33 substrate Elasticmodulus at 25° C. (mPa) 120 120 120 88 120 120 120 Yield elongation at25° C. 24 24 24 8 24 24 24 Name POF-120A POF-120A POF-120A DDD POF-120APOF-120A POF-120A

TABLE 2 Ex. 8 Ex. 9 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4Adhesive (A) High molecular HTR-860-P3 100 100 100 100 100 100 bondinglayer weight component HTR-860-P5 — — — — — — (B) Epoxy resin YDCN-7035.4 5.4 5.4 5.4 5.4 5.4 EXA-4850 — — — — — — YDF-8170 16.2 16.2 16.216.2 16.2 16.2 (C) Curing agent LF2882 15.3 15.3 15.3 15.3 15.3 15.3 (D)Photoreactive A-DPH (250° C. or more) — 30 — — — 30 monomer A-9300 (250°C. or more) 30 — — — — — (Brackets indicate Tg.) BPE-200 (75° C.) — — 30— — — FA-321M (150° C. or less — — — 30 — — (E) Photoinitiator I-369 1.51.5 1.5 1.5 1.5 — I-907 — — — — — — Silane coupling agent NUCA-189 0.10.1 0.1 0.1 0.1 0.1 NUCA-1160 0.3 0.3 0.3 0.3 0.3 0.3 90° peel strength(N/m) after UV irradiation 4 2 10 No peeling No peeling No peeling Tackstrength at 25° C. prior to UV irradiation 103 46 352 244 21 87Supporting Surface energy (mN/m) 33 33 33 33 33 33 substrate Elasticmodulus at 25° C. (mPa) 120 138 120 120 120 120 Yield elongation at 25°C. 24 20 24 24 24 24 Name POF-120A FHF-100 POF-120A POF-120A POF-120APOF-120A

TABLE 3 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Evaluation Stickingproperties at room temperature A A A A A A A Chip scattering afterdicing None None None None None None None Pickup properties A A A A A AA Shearing adhesion strength 3.26 1.11 2.21 3.04 2.99 2.88 3.10 Reflowcracking resistance 0/10 0/10 0/10 0/10 0/10 0/10 0/10 T1 (° C.) 40 4040 60 40 40 40 α1 (ppm/° C.) 264 264 264 266 264 264 264 T2 (° C.) 25 2525 25 25 25 25 α2 (ppm/° C.) 264 264 264 266 264 264 264 T1 × α1 − T2 ×α2 (ppm) 3960 3960 3960 9310 3960 3960 3960

TABLE 4 Ex. 8 Ex. 9 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4Evaluation Sticking properties at room temperature A A A A A A Chipscattering after dicing None None None None None None Pickup propertiesA A B C C C Shearing adhesion strength 5.60 3.26 1.08 2.85 3.52 1.32Reflow cracking resistance 0/10 0/10 10/10 8/10 0/10 10/10 T1 (° C.) 4060 40 40 40 40 α1 (ppm/° C.) 264 1460 264 264 264 264 T2 (° C.) 25 25 2525 25 25 α2 (ppm/° C.) 264 568 264 264 264 264 T1 × α1 − T2 × α2 (ppm)3960 73400 3960 3960 3960 3960

From the above results, it is also seen that in Examples 1-9, the roomtemperature sticking properties, chip scattering after dicing, pickupproperties and reflow cracking resistance are satisfactory, but inComparative Examples 1 and 2, Tg of the cured product obtained byultraviolet light irradiation of the photoreactive monomer is low, sothe reflow resistance is poor. It is also seen that, in ComparativeExample 3, the photoreactive monomer is not present, so pickupproperties after ultraviolet light irradiation are poor, whereas inComparative Example 4, the photoinitiator is not present, so pickupproperties after ultraviolet irradiation are poor, and as unreactedphotoreactive monomer is present, reflow resistance is poor.

INDUSTRIAL APPLICABILITY

Since the photo-curing adhesive bonding sheet of the present inventionhas the aforesaid structure, it has superior room temperature stickingproperties, dicing properties and reflow cracking resistance, so it issuitable for use as an adhesive resin for fixing electronic materials.

1. An adhesive bonding sheet having an optically transmitting supporting substrate and an adhesive bonding layer, and capable of being used in both a dicing step and a semiconductor element adhesion step, wherein the elastic modulus of the supporting substrate at 25° C. is 1000 MPa or less, and wherein the adhesive bonding layer comprises (a) a polymer component having a weight average molecular weight of 100,000 or more including functional groups, (b) an epoxy resin, (c) an epoxy resin curing agent, (d) a photoreactive monomer, wherein the Tg of cured material of the photoreactive monomer, obtained by ultraviolet light irradiation, is 250° C. or more, and (e) a photoinitiator.
 2. The adhesive bonding sheet according to claim 1, wherein the polymer component is a (meth)acrylic copolymer comprising 0.5-6 weight % of epoxy group-containing repeating units based on the total weight of the polymer component.
 3. The adhesive bonding sheet according to claim 1, wherein usage amount of the epoxy resin is 5-250 weight parts relative to 100 weight parts of the polymer component.
 4. The adhesive bonding sheet according to claim 1, wherein the surface free energy of the supporting substrate is 50 mN/m or less.
 5. The adhesive bonding sheet according to claim 1, wherein the 90° peel adhesion strength after ultraviolet irradiation of the adhesive bonding layer relative to the supporting substrate is 10 N/m or less. 